Dry seal pressure type gasholder



Feb. 12, 19 52 J. H. WIGGINS DRY SEAL PRESSURE TYPE GASHQLDER Filed July 24, 1947 Q :l m I u m m; m m w n k N l T w m w m u m w u m U A H LM l||i v llllll v IIIL n T v v IN VENT 0R JOHN H. WIGGINS R 5, ma M A TTORNE'Y to assume a certain approximate shape or form during the rise and fall of the piston and to absorb pressure exerted on said piston sealing element by the gases in the storage space or chamber, is formed by an annular or tubularshaped member F mounted on the top side of the piston D. Said member F is provided at its top and bottom edges with rounded or convexed surfaces, formed preferably by round rods and 6, respectively, welded to said member, and at the upper end of said member F there is an annular compression member I that imparts rigidity to same.

My improved gas holder is distinguished from prior gas holders of the general type mentioned in several respects:

(1) The overall length, depth, or height of the backing and reinforcing member F on the piston is considerably less than the depth or height of backing members attached to the pistons of prior dry seal, pressure type gas holders; and said member is so proportioned and arranged with relation to the flexible, curtain-like sealing element E with which it co-acts, that when the piston is in its lowermost position, the top edge of the backing member F will be located a substantial distance below the point at which said sealing element is attached to the side wall of the container. This enables the overall height of the container side wall to be correspondingly reduced and the amount of metal saved in shortening the backing member F on the piston, and lowering the container side wall, effects a considerable saving in the cost of constructing the apparatus.

(2) The piston structure, composed of the piston D and backing member F, is of such design that slack or fullness which exists in the piston sealing element E when the gas chamber is empty, will not cause sharp bends, folds or deep wrinkles to form in said sealing element when pressure is subsequently created in the gas chamber, and said pressure forces said sealing element into snug engagement with the piston structure. The third distinguishing characteristic of my improved apparatus is that the pis on sealing element E is attached to the piston structure in a novel manner that facilitates the installation or removal of said element and enables the joint between same and the piston structure to be readily inspected for leaks, as previously explained.

In my improved apparatus the inner edge of the sealing element E is attached to the piston structure at a point above the bottom face of the piston D and an annular, horizontally-disposed gap, cavity or opening is formed in the piston structure above the point of attachment of the sealing element E to the piston structure, so as to provide a relief space into which a portion of the sealing element E will be forced or flexed by the pressure of the gases in the storage chamber when the piston is in its lowermost position, shown in solid lines in Figure 1. In the accompanying drawings, the above-mentioned, horizontally-disposed gap, cavity or opening in the piston structure is designated by the reference character M, and said gap is produced by attaching the backing member F to the piston by a plurality of upwardly-projecting brackets or supporting arms 9 on the top side of the piston, designed or proportioned so that the bottom edge of the member F will be separated by a gap M from the horizontal flange on the rim 8 of the piston, to which the sealing element E is clamped by the annular clamping member 4 through which the bolts 3 pass. The backing member F is of such height, depth, or length, that when the piston is in its lowermost position, the top edge of said member F will be located a substantial distance below the horizontally-disposed clamping bar 2, which secures the outer edge portion of the sealing element E to the side wall of the container. In the drawings the reference character H designates the net height of the backing member F, the reference character K designates the distance that the top edge of said backing member is below the horizontal row of the bolts I in the container side wall when the piston is resting on the bottom C of the container, the reference character X designates one-half of the stroke of the piston from its lowermost to its uppermost position, and the reference character Y designates the height of the rim 8 on the piston to which the sealing element E is attached. In the enlarged views, Figures 2 and 3, the reference character R designates the maximum radius of the sealing element E in the space K between the top edge of the backing member F and the point of attachment of the outer edge of the piston sealing element to the container side wall, and the reference character R designates the radius of the piston sealing element at the gap M between the bottom edge of the backing member F and the point of attachment of the inner edge of the piston sealing element to the rim 8 on the top side of the piston. The accompanying drawings are intended to illustrate the principle of operation of an apparatus embodying my invention and not the exact relative proportions of the co-acting parts of the apparatus, but usually the distance K will be of the order of 2 feet to 4 feet, depending upon the internal pressure of the gas and the overall diameter of the container of the apparatus, the distance Y representing the height of the rim 8 on the piston, will be of the order of 2 inches to 3 inches, the vertical height of the gap M will be of the order of 3 inches to 6 inches, the radius R will normally be a maximum of 3 feet to 6 feet, the radius R will be of the order of 3 inches to 6 inches, and the distance X representing one-half the rise of the piston will vary from a few feet to 50 or even feet.

Since the tension in the piston sealing element E is directly proportional to the radii R and R for any given pressure and completely independent oi the radius of the container, it will be seen that for pressures of the order of 4 inches to 12 inches of water, which is the normal pressure at which gas holders of the type herein described operate, the tension is very low, being of the order of 15 pounds to 20 pounds per linear inch, circumferentially of the piston sealing element. Since such piston sealing elements ar capable of withstanding tensions of pounds to 250 pounds per linear inch, it is obvious that these tensions are far on the safe side for successful operation of the apparatus. Usually, the piston sealing element will be made up with an asbestos cloth core having about 85% asbestos and 15% glass fibre coated on each side with a synthetic rubber that is keyed through the cloth in such a way as to make the cloth very strong and very pliable.

In the normal operation of the apparatus, as the piston moves upwardly off the bottom of the container, the radius R of the piston sealing element becomes progressively smaller, as is shown in Figure 3, until said radius finally disappears when the piston sealing element is laid against the container side wall above the horizontal row of bolts l at the completion of the upward stroke of the piston, as shown in broken lines in Figure 1. Also the radius R of the piston sealing element has disappeared, since the piston sealing element is now lying entirely against the side wall of the container. As the piston moves downwardly from its uppermost position, shown in broken lines in Figure 1, the piston sealing element E will feed back into the annular gap or space M in the piston structure and then roll up onto the outside face of the backing member F, finally assuming the approximate shape or form shown in full lines in Figure 1 by the time the piston reaches the end of its downward stroke.

When there is no internal pressure in the gas space of the apparatus, the piston sealing element E will hang downwardly in substantially parallel relation to the side wall of the container, as indicated by the broken lines in the lower portion of Figure 1. Usually, the piston sealing element will be made from 1 inch to 3 inches longer than the actual distance between the line of bolts I and the line of bolts 3 that attach the outer and inner edges of the piston sealing element to the container side wall and to the piston, respectively, and consequently, when there is no pressure in the gas space of the apparatus, there is a-certain amount of slack or fullness inthe inner edge portion of the piston sealing element E.

In a pressure type gas holder of conventional design, slack or fullness of the kind above referred to would be very detrimental and would cause the piston sealing element to rupture, due to sharp folds or bends forming in the full portion or slack portion of said sealing element, whenever pressure is created in the storage chamber. To state it in another way, if the piston sealing element of a gas holder of conventional design were made from one to three inches longer than is the usual practice, the weight of said sealing element would cause all of the excess material in same to accumulate at the inner edge portion of the sealing element when the storage chamber is under no pressure. Subsequently, when pressure is created in the storage chamber, the pressure would cause the slack or excess material in the piston sealing element to double onto itself and produce a substantially S-shaped, circumferentially-disposed wrinkle of such sharp radii, that the material of which the piston sealing element is constructed would eventually rupture, due to the strain imposed on said material by the sharp bends created in the slack or fullness at the inner edge of said element when the storage chamber is under no pressure. My invention makes it practicable or feasible to have slack or fullness in the piston sealing ele-- ment E, due to the fact that the piston structure is provided with a gap M that effectively takes care of said slack or fullness and eliminates sharp S-shaped, circumferentially-disposed wrinkles forming in the piston sealing element. When the gas pressure is first applied to the piston sealing element, said element is forced into snug engagement with the outside surface of the backing member F, the outer edge portion of said sealing element stretching slightly to attain the radius R Such piston sealing elements, however, are made so that they stretch a substantial percentage of their length at comparatively low unit stresses. During the upward stroke of the piston the sealing element E will be stripped off the backing member F and laid onto the container side wall, as previously explained.

I wish it to be understood that my invention is applicable to a dry seal, pressure-type gas holder equipped with a backing and reinforcing structure for the piston sealing means composed of a vertically-shiftable, annular backing member arranged in the space between the piston and the container side wall, and a co-acting, annular backing member rigidly attached to the piston and adapted to be disposed in telescoped relationship with the above mentioned verticallyshiftable backing member, either at all times, or only at certain periods in the cycle of opera tions of the piston. In such a backing and re inforcing structure, both the vertically-shiftable backing member and the backing member on the piston would be shortened or reduced in length,

an amount or degree corresponding to the previously described distance K, i. e., the distance representing the amount which the backing member attached to the piston of my apparatus is reduced in length and height in comparison with the piston supported backing members heretofore used in dry seal, pressure type gas holders.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A fluid storage apparatus, comprising a container provided with a vertical side wall, a vertically- -movable piston in said container, a curtain-like sealing member attached to the piston and to the container side wall, the height of said sealing member exceeding the distance between the line at which the sealing member is attached to the container side wall and the line at which said sealing member is attached to the piston when said piston is in its lowermost position, and a backing member rigidly attached to said piston, the lowermost portion of the backing member lying above the piston, thereby forming a gap into which the lower end of the sealing member is adapted to be flexed by pressure of fluid stored in the container.

2. An apparatus of the kind described in claim 1, in which the piston is provided with a means, accessible from the top side of the piston, for detachably connecting the sealing member to the piston.

' JOHN H. WIGGINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 619,510 Sergeant Feb. 14, 1899 633,427 Cooper Sept. 19, 1899 2,194,604 Malsbary Mar. 26, 1940 2,363,565 Wiggins Nov. 28, 1944 2,494,601, Wiggins Jan. 17, 1950 FOREIGN PATENTS Number Country Date 4,790 Great Britain' 1823 

